Crane boom guard attachment



June 20, 1961 A. J. THOMAS 2,989,194

CRANE BOOM GUARD ATTACHMENT Filed Sept. 25, 1959 2 sheet sheet 1 INVENTOR 5 15111 Jfi DMAJ June 20, 1961 A. J. THOMAS CRANE BOOM GUARD ATTACHMENT 2 Sheets-Sheet 2 Filed Sept. 25, 1959 United States Patent 2,989,194- CRANE BOOM GUARD ATTACHMENT Arthur J. Thomas, Little Rock, Ark., assignor to Saf-T- Boom Corporation, Little Rock, Ark., a corporation of Arkansas Filed Sept. 25, 1959, Ser. No. 842,435 6 Claims. (Cl. 212-1) This invention relates generally to insulating apparatus and more specifically to a safety device or guard for crane and well drilling machines, etc. having high booms, and is a continuation-in-part of my application, Serial No. 711,063, filed January 24, 1958, now Patent No. 2,950,016, entitled Crane Boom Guard Attachment.

Despite the added caution exercised by crane operators when Working adjacent high voltage electric lines, the booms are too often accidentally moved into contact therewith resulting in death or serious injury to the operator and other persons and in a short circuit and damage to the electric line.

The chief object of the present invention is to provide a readily attachable safety device in the form of a guard for the booms of cranes and well drilling machines which will eliminate danger and injury to the operator and other workmen such as pipe fitters, iron workers, bystanders, etc. as well as damage to electric lines from short circuits when a crane boom is accidentally or otherwise moved into contact with such lines.

Another important object of the present invention is to provide a light-weight guard for crane booms which is formed of insulated members so as to render it impossible to short circuit electric lines when in contact therewith.

A further important object of the present invention is to provide a guard for crane booms which is mounted on the boom and insulated therefrom so as to prevent the transmission of electric currents to the boom, its operator, and other adjacent persons.

A still further important object of the present invention is to provide a strong, lightweight, readily attachable guard for crane booms which is pivotally mounted so as to accommodate for the changing angle between the boom and the gantry cables and which is partially supported by and effects a minimum of wear to the gantry cables.

Another important object of the present invention is to provide a guard of the type described for telescopic crane, etc. booms which includes novel mounting means to enable the guard to be readily attached to such a boom without interfering with the extension or retraction of its telescoping sections.

Another object of the present invention is to provide a guard of the type described which will be susceptible of ready and economical manufacture, and will be rugged and of long life in use.

Other objects and advantages of the present invention will become apparent during the course of the following description.

In the drawings, I have shown one embodiment of the invention. In this showing:

FIGURE 1 is a side elevational view of the outer end of a crane boom showing the guard comprising the present invention in operative position thereon;

FIGURE 2 is an upper end elevational view thereof to an enlarged scale;

FIGURE 3 is a lower end elevational view thereof looking along the lines 3-3 of FIGURE 1;

FIGURE 4 is a side elevational View of one of the inner end supports to a further enlarged scale;

FIGURE 5 is 'a fragmentary view looking on the line 5-5 of FIGURE 2 and showing the upper end mounting of the guard on a boom;

FIGURE 6 is a sectional view to a further enlarged scale of one of the guard frame members taken on the line 6-6 of FIGURE 4;

FIGURE 7 is a side elevational view to a reduced scale of a vehicle-mounted, extensible crane boom in retracted position showing the guard comprising the present invention in operative position thereon;

FIGURE 8 is a side elevational view to an enlarged scale showing the outer end of the boom and the means of attaching the guard to the extensible boom sections to permit their extension or retraction, the boom being extended;

FIGURE 9 is a transverse, vertical sectional view thereof, partly in elevation, to a further enlarged scale, taken on the line 99 of FIGURE 8; and

FIGURE 10 is a similar view taken on the line 1010 of FIGURE 8.

In its broadest aspects, the present invention contemplates a guard for crane booms which will prevent the shortcircuiting of electric lines against which it may be moved, and which will prevent the transmission of electric currents from such lines along the crane boom to the operator.

Referring to the drawings, numeral 10 designates the crane boom guard as a whole which comprises a frame formed of a plurality of laterally spaced, longitudinally extending rods 12 connected at spaced intervals by semicircularly extending rods 14 to thus form a hood which extends from a point above the boom B and the gantry cables C outwardly and downwardly with respect thereto (FIGURES 1-3).

The two lowermost rods 12 may be formed of a single U-shaped rod with the base of the U forming the round guard portion 16 at the upper end of the frame. Similarly, the upper rods 12 terminate in semi-circular portions 18 at the upper end of the frame to extend it below the end of the boom and terminate at and are fixed to a semicylindrical extension 20 of the uppermost rod 14 which is thus circular.

The upper end of the guard frame 10 is supported on the end plate 22 of the boom B by a base plate 24 angularly disposed with respect to the plate 22 and welded thereto, and a pair of spaced insulators 26 is fixed to the base plate 24 and to a rod 28 pivotable in a collar 30 which is welded to a rod 32 spanning the rods 18.

The lower end of the guard 10 (FIGURES 1, 3 and 4) includes a pair of spaced insulators 34 fixed to and depending from the upper, longitudinally extending rods 12. A pulley 36 is fixed to the bottom of each of the insulators 34 and each bears and rotates on one of the gantry cables C. The pulleys 36 are preferably closed at their bottoms to prevent accidental displacement of the pulley wheels from the cables, the weight of the guard. frame 10 normally preventing such displacement.

As seen in FIGURE 6, the exterior of the frame rods 12, 14, etc., is coated with an insulating plastic or ceramic material 40 which prevents the frame members of the guard 10 from short circuiting any power lines which it may contact. The insulators 26 and 34 are preferably standard 50,000 volt insulators of 5,000 lbs. drop test so as to be of adequate electrical resistance and mechanical strength.

The guard is readily applicable to extensible booms of any type such as, for example, the telescopic type used by outdoor advertising firms, etc. These vary but a common form as shown in FIGURE 7 comprises a boom 42 having inner extensible, telescoped sections '43 and 44; and pivotally mounted about av horizontal axis on a vehicle mounted base 45 which is rotatable in a horizontal plane.

The boom is pivoted from the horizontal position shown. to an almost vertical position by means of a hydraulic jack 46. The extension of the telescoped sections is effected hydraulically while retraction is effected by cables 47 connected to pulleys in upstanding pulley housings 48 mounted on the outer ends of the sections 43 and 44, the

Patented June 20, 1961 3 exact details of which are not shown inasmuch as they are conventional.

The guard 50 shown in FIGURES 7-10 inclusive is substantially identical with the guard 10 of FIGURES 1-6 inclusive and varies in cross-sectional shape in that additional longitudinally extending, vertically spaced rods 12' are used to form a guard having an inverted U crosssection and the circular portions 18 are extended inwardly as at 19 for approximately a third of the length of the guard and bent upwardly to join a connecting, transverse rod 15. This provides an outer end, depending guard portion protecting the hoist pulley 49 mounted at the outer end of the telescopic section 44.

The guard 50, adjacent its outer end, is connected to and supported by an insulator 52 by a transverse arcuate strap 54 welded to the two uppermost of the longitudinally extending rods 12. The lower end of the insulator is rigidly connected to and supported by a clamp 56 fixed to the outer telescopic section 44 so that the guard 50 moves to extended or retracted position with the section 44.

The inner end of the guard 50 is connected to and supported by an insulator 58 by a transverse strap 55 (FIG- URE 9) welded to the longitudinal rods 12' and the insulator is fixed to an inverted U-shaped frame 60 mounting a pair of spaced pulleys 62 which are supported on and track along a pair of transversely spaced, longitudinally extending rods 64. At their outer ends, (FIGURE 8) the rods 64 are supported on the telescopic section 43 by means of a connecting plate 66 welded to both the rods and the section 43.

The inner ends of the rods 64 are slidably received within and supported by a pair of transversely spaced, longitudinally extending tubes 68 which are supported adjacent their ends by other connecting plates 66 (not shown) welded thereto and to the telescopic section 42. The pulley frame 60 terminates in a pair of arcuate guard portions 61 to prevent the accidental displacement of the pulley wheels 62 from the rods 64 and, as will appear, from the tubes 68.

The boom guard 50 is of greater length than the outer telescopic section 44 so that when extended as seen in FIGURE 8, the guard is supported on the outer end of the telescopic section 44 and at its inner end on the rods 64. As, the telescopic section 44 is retracted into the section 43, the pulleys roll along the rods 64 and transfer to and roll on the tubes 68. When the section 43 is retracted into section 42, the pulleys continue to roll inwardly on the tubes 68- while the rods 64 move within the tubes which are of adequate length to house the rods when the telescopic boom sections are fully retracted.

Thus, it will be readily apparent that the guard 50 moves smoothly with the telescopic boom during extension or retraction without interference therewith while fully protecting the end, top and sides of the boom from contact with power lines, obstructions, etc.

It will now be apparent that the novel boom guards described comprise very important safeguards for the booms of cranes and well drilling machines, may be readily attached and will not effect any wear or tear on the gantry lines during operation, nor interfere with the operation of telescoping booms.

It is to be understood that the forms of the invention herewith shown and described are to be taken as preferred examples of the same and that various changes in the shape, size and arrangement of parts may be resorted, to without departure from the spirit of the invention or the scope of the sub-joined claims.

I claim:

1. For use on a boom having relatively movable sections, a guard for preventing said sections from contacting a power line, said guard comprising an elongated frame extending in protecting relation over the top, sides and end of said boom, insulated mounting means on said frame securing it to one of said movable sections for movement therewith when the boom is extended, and

insulated guide means on said frame guidingly engaging another section of said boom and facilitating movement of said frame during extension and retraction of said boom.

2. A guard for preventing the extensible boom of a crane, etc. having relatively movable sections from contacting a power line when moved thereagainst comprising an elongated frame of spaced, connected members adapted to project outwardly from the top, sides and end of the boom, means for mounting said frame on the outer sections of the, boom for movement therewith during extension and retraction thereof, a rod fixed to and extending along one of the relatively movable sections, said frame mounting means comprising an outer rigid connection between said frame and another of the movable sections, and a pulley fixed to and supporting the inner end of said frame by resting on and tracking along said rod during relative movement of said sections.

3. A guard for preventing the extensible boom of a crane, etc. having relatively movable sections from contacting a power line when moved thereagainst comprising an elongated frame of spaced, connected members adapted, to project outwardly from the top, sides, and end of the boom, means for mounting said frame on the outer sections of the boom for movement therewith during extension and retraction thereof, a tube fixed to and extending along one of the relatively movable sections, a rod fixed to and extending along another of said movable sections and slidably received in said tube, and said frame mounting means comprises an outer rigid connection between said frame and still another of said movable sections, and a pulley fixed to and supporting the inner end of said frame by resting on said rod in the extended position of the boom and tracking along said rod onto said' tube to the retracted position thereof.

4., A guard adapted to be interposed between an extensible boom of a crane, etc. having relatively movable sections comprising an elongated frame of spaced, connected, rod-like members, and means mounting said frame in spaced relation from the sides and top of the boom with one end of said frame extending beyond the outer end of the boom whereby engagement with a power line is had by the frame, said mounting means comprising an insulated outer rigid connection between said frame and the outermost of said relatively movable sections, at least one rod fixed to and extending along another of said sections, and at least one insulated pulley fixed to and supporting the inner end of said frame by being rotatably supported on said rod.

5. A device as recited in claim 4 wherein at least one tube is fixed to and extends along still another of said sections and slidably receives said rod whereby said pulley is first rotatable over said rod and then over said tube during retraction of the boom.

6. In combination, an extensible boom having relatively movable sections, a guard mounted on said boom in spaced surrounding relation to a portion of the boom and the terminal end thereof, and electrical insulating means interposed between said guard and said boom for preventing the transmittal of current therebetweeu upon accidental, contact of said guard with a current conductor, said guard comprising a skeletonized framework extending longitudinally of said boom and beyond the terminal end thereof, said framework being supported at its outer end by an insulated, rigid connection with one of said relatively movable sections and at its inner end by an insulated pulley supported on and adapted to traverse along another of said relatively movable sections.

References Cited in the file of this patent UNITED STATES PATENTS 

